Engineering topics

Cutler, E. P.

Publications and source records attributed to Cutler, E. P..

8 records

NASA NTRS1986

An elliptical binary orbit model of GX 1 + 4

The X-ray source GX 1 + 4 (4U 1728-24) was observed by the high-energy X-ray spectrometer on OSO 8 for five days from September 20-24, 1978, and X-rays in the energy range 16-72 keV were analyzed. Measurements of the pulse period, pulsar angular acceleration, and luminosity of GX 1 + 4 are reported. The pulsar light curves obtained in different energy ranges are presented, and it is concluded that the period is about 220 s rather than about 110 s. The observations are combined with those reported by others, and a history of GX 1 + 4 as observed in hard X-rays is presentd. A continuous function for the change in period is inferred that suggests a 304-day periodicity. It is proposed that such a period in the spin-up could be caused by an elliptical orbit of GX 1 + 4 abouts its red giant companion.

Cutler, E. P.↗

NASA NTRS1984

Design and implementation of a compliant robot with force feedback and strategy planning software

Force-feedback robotics techniques are being developed for automated precision assembly and servicing of NASA space flight equipment. Design and implementation of a prototype robot which provides compliance and monitors forces is in progress. Computer software to specify assembly steps and makes force feedback adjustments during assembly are coded and tested for three generically different precision mating problems. A model program demonstrates that a suitably autonomous robot can plan its own strategy.

Premack, T.↗

NASA NTRS1980

Detection of high-energy X-rays from the galactic center region

Results are presented from repeated scans of the galactic center region made with the high-energy X-ray detector on OSO 8 during the five days of Sept. 20-25, 1978. The observations show a strong flux of high-energy excluding GX 1 + 4 and GX 3 + 1. The photon-number spectrum of this flux is harder than that of GX 1 + 4 measured during the same interval.

Dennis, B. R.↗

NASA NTRS1979

Detection of high energy X-rays from the galactic center region

Observations of the galactic center region made with the high energy X-ray detector on OSO-8 are discussed. A strong hard X-ray which was detected during these observations from the vicinity of the galactic center are examined. The counting rate spectrum and the photon number spectrum of the flux are determined. Comparisons with the high energy X-ray fluxes observed from sources in the region by others are discussed.

Dennis, B. R.↗

NASA NTRS1979

The high-energy pulsed X-ray spectrum of Hercules X-1 as observed with OSO 8

Hercules X-1 was observed from August 30 to September 10, 1977, by using the high-energy X-ray scintillation spectrometer on board the OSO 8 satellite. The observation, during which the source was monitored continually for nearly an entire ON-state, covered the energy range from 16 to 280 keV. Pulsed-flux measurements as a function of binary orbit and binary phase are presented for energies between 16 and 98 keV. The pulsed flux between 16 and 33 keV exhibited a sharp decrease following the fourth binary orbit and was consistent with zero pulsed flux thereafter. Only weak evidence was found for temporal variation in the pulsed flux between 33 and 98 keV. The pulsed spectrum has been fitted with a power law, a thermal spectrum without features, and a thermal spectrum with a superposed Gaussian centered at 55 keV. The latter fit has the smallest value of chi-square per degree of freedom, and the resulting integrated line intensity is approximately 0.0015 photon/sec per sq cm for a width of 3.1 (+9.1, -2.6) keV. This result, while of low statistical significance, agrees with the value observed by Truemper (1978) during the same ON-state.

Maurer, G. S.↗

NASA NTRS1978

The high-energy pulsed X-ray spectrum of HER X-1 as observed with OSO-8

Her X-1 was observed from 1977 August 30 to September 10 using the High-Energy X-Ray Scintillation Spectrometer on board the OSO-8 satellite. The observation, during which the source was monitored continually for nearly an entire ON-state, covered the energy range from 16 to 280 keV. Pulsed flux measurements as a function of binary orbit and binary phase are presented for energies between 16 and 98 keV. The pulsed flux between 16 and 33 keV exhibited a sharp decrease following the fourth binary orbit and was consistent with zero pulsed flux thereafter. The pulsed spectrum was fitted with a power law, a thermal spectrum without features, and a thermal spectrum with a superposed gaussian centered at 55 keV. The latter fit has the smallest value of chi - squared per degree of freedom, and the resulting integrated line intensity is 1.5 superscript + 4.1 subscript - 1.4 x .001 photons s superscript-1 cm superscript-2 for a width of 3.1 superscript + 9.1 subscript -2.6 keV. This result, while of low statistical significance, agrees with the value observed by Trumper (1978) during the same On-state.

Maurer, G. S.↗

NASA NTRS1978

High energy X-ray spectrum of Her X-1

Line features in the high-energy X-ray spectrum of Her X-1 are attributed to an approximately 1% change in detector gain. The spectrum was obtained by a high-energy X-ray detector aboard OSO-8. The time-averaged spectrum of Her X-1 for the period August 31-Sept. 6, 1977 is presented; the count-rate spectrum was corrected for an average change in gain of 0.7%. The best fit power-law is reported.

Dennis, B. R.↗

NASA NTRS1978

Upper limits on the cyclotron lines from Her X-1 as observed with OSO-8

Observations of Her X-1 were obtained during its ON-state in September, 1977, with the high-energy X-ray detector on board OSO-8. Upper limits on the line fluxes at 60 and 135 keV based on these observations are above, and hence consistent with, the positive results reported by Trumper, et al from a balloon flight during the same time interval. A detailed analysis of the time-variable et al background spectrum suggests that the line emission, especially in the time-averaged spectrum of Her X-1 previously reported by other workers at 25, 60, and 135 keV, is due to instrumental effects. The spectrum obtained with OSO-8 in September, 1977, is considerably steeper than that observed in pre-1976 balloon flights. These results are consistent with the results obtained by Trumper showing a decrease in the effective temperature of Her X-1 between May, 1976, and September, 1977.

Dennis, B. R.↗